NEB Class 11 • Physics • Focused Revision

Quantity of Heat Study Guide: NEB 11 Physics

Make system boundaries and energy direction visible before using any equation. Practise single-stage, mixture and phase-change problems with an error-led review plan.

Eight-session mastery sequence
Energy-ledger and calorimetry routines
Experiments, timed set and spaced correction

Quantity of heat is energy transferred across a system boundary.

Learning target

What successful study looks like

Use the CDC Physics Grade 11 page and secondary curriculum for Nepal scope. Use the OpenStax heat-capacity section and calorimetry reference to compare definitions, examples and conservation methods.

Success means you can translate a description into a system boundary and staged energy ledger without being told the equation. The paired Quantity of Heat concept guide is for rebuilding theory; this page focuses on deliberate practice.

Decision map

Ask what changes before selecting Q

Temperature changes

One phase, constant c approximation: Q=mcΔT.

Whole object

Known heat capacity: Q=CΔT.

Phase changes

Ideal plateau: Q=mL.

Objects exchange

Write one term per body or stage and apply ΣQ=0.

Add a fifth branch for electrical or mechanical input. If power P acts for time t, energy is Pt; only the fraction transferred to the chosen body belongs on its heating side.

Eight focused sessions

Quantity of Heat learning sequence

Session	Focus	Evidence
1	Heat, internal energy, temperature	Ten precise statement repairs
2	c, C and Q=mcΔT	Eight direct/reverse calculations
3	Two-body calorimetry	Five signed heat ledgers
4	Calorimeter/container terms	Three model comparisons
5	Latent heat and heating curves	Six stage-identification tasks
6	Multi-stage mixtures	Four complete energy pathways
7	Electrical experiment and uncertainty	Method, graph and bias explanation
8	Timed mixed paper	80% plus corrected error log

Use a 55-minute block: ten minutes retrieval, ten minutes targeted review, thirty minutes problems and five minutes error coding. Interleave an earlier problem at the start of each new session.

Central routine

Build the energy ledger before algebra

Draw every body inside the system boundary.
Record mass, initial temperature and phase.
Predict which terms gain and lose energy.
Draw arrows from initial to final state.
Break every phase boundary into a separate segment.
Attach mcΔT, mL or CΔT to each segment.
Apply conservation and solve.
Check final state and range.

Ledger example

Hot metal enters cool water in a cup. The ideal ledger is Q_metal+Q_water+Q_cup=0. If the cup begins with the water, both warming terms use the same T_f−T_i. Omitting the cup is a deliberate approximation that must be stated.

Calculation fluency

Direct, reverse and comparison drills

Direct energy

0.40 kg copper with c=390 J kg⁻¹K⁻¹ warms by 60 K. Q=0.40×390×60=9360 J.

Find temperature rise

15 kJ heats 0.50 kg material with c=600. ΔT=15000/(0.50×600)=50 K.

Find unknown mass

25.2 kJ warms water by 15 K with c=4200. m=25200/(4200×15)=0.40 kg.

Ratio without calculation

For equal Q and c, doubling mass halves ΔT. Write the proportionality ΔT∝1/m before inserting numbers.

After each calculation, write a sentence: “Energy entering is positive,” “larger heat capacity causes smaller temperature rise,” or another physical check. This exposes unit-correct but model-wrong answers.

Calorimetry practice

Use range and capacity checks

Equal material masses

Equal masses of the same liquid at 70°C and 30°C mix ideally. Equal heat capacities give T_f=50°C. This shortcut fails if masses or specific heats differ.

Unequal heat capacities

Body A has C=200 J K⁻¹ at 90°C; B has C=600 J K⁻¹ at 20°C. 200(90−T)=600(T−20), giving T=37.5°C. The final value lies closer to B’s initial temperature because B has the larger heat capacity.

Three quick checks: final temperature must normally lie between starting temperatures, energy lost and gained must have equal magnitude in the ideal boundary, and a very large heat capacity should move little.

Stage-by-stage mastery

Read and build heating curves

Sloping segments usually represent temperature change within one phase and use mcΔT. Ideal horizontal plateaus represent phase change and use mL. The gradient of a temperature-versus-energy graph also depends on mc, so do not interpret every slope change as a phase change without labels.

Ice at −10°C to water at 30°C

Write Q=m c_ice(10 K)+mL_f+m c_water(30 K). Keep three terms, their material properties and their temperature intervals separate.

Does all the ice melt?

First calculate energy available from the warm body cooling to 0°C. Compare with energy required to warm ice to 0°C and melt it. Only if enough remains may the resulting water rise above 0°C.

Use the OpenStax latent heat reference to practise phase boundaries and energy conservation.

Experimental study

Extract c from an electrical-heating graph

For approximately constant heater power P and negligible loss, P=mc(dT/dt). Therefore the temperature–time gradient s gives c=P/(ms). Real graphs curve because heat loss grows as the block becomes hotter than surroundings. Use an early interval or a corrected model and state the choice.

Error	Code	Correction
Used 25°C instead of ΔT	interval	Write T_f−T_i
Forgot cup energy	boundary	Draw every object in the system
Used mcΔT during melting	stage	Mark phase plateaus before equations
Mixed grams and kilograms	unit	Convert on a data line first
Final T above hottest initial body	range	Recheck signs and external input

Use PhET Energy Forms and Changes for prediction–observation–explanation practice, especially how different materials respond to comparable energy input.

Spaced correction

Turn mistakes into a revision schedule

Code the first wrong decision as language, boundary, direction, equation, stage, unit, range or algebra. Redo after one day with changed values, after three days in a mixed set and after seven days from a diagram only. If the same code returns, explain the model aloud before another calculation.

Connect this topic to Work, Energy & Power: both use conservation, but heat and work describe different transfer mechanisms. Connect it to Heat & Temperature for equilibrium and transfer mechanisms.

Final assessment

Exam checklist and unseen test

Heat is described as transfer, not stored content.
System boundary and sign convention are explicit.
c and C have distinct meanings and units.
Every body and phase stage has its own energy term.
Final temperature passes a range check.
Electrical input is distinguished from energy reaching the sample.
Uncertainty direction is explained, not merely named.

Repair three incorrect heat statements.
Solve one direct and one reverse Q=mcΔT problem.
Solve a two-body mixture with unequal heat capacities.
Build a three-stage phase ledger.
Evaluate an electrical-heating method.

Aim for 80% or more with no repeated boundary, stage or sign error. For online or physical NEB tuition, call 9846662070.

Frequently asked questions

Questions about studying Quantity of Heat

What should I write before an equation?

Define the system, list each body and phase, and predict which terms gain and lose energy.

How do I know whether to use mcΔT or mL?

Use mcΔT when temperature changes within one phase and mL during an ideal phase change at fixed temperature.

Why include the calorimeter?

It can absorb or release a meaningful amount of energy, changing the final temperature or inferred specific heat.

How do I check a mixture answer?

Without an external source or phase complication, the final equilibrium temperature should lie between initial temperatures and energy lost should equal energy gained.

How often should I redo errors?

Retest after one, three and seven days with changed numbers and a mixed problem order.

Where can I get NEB Quantity of Heat tuition?

For current online or physical options, call 9846662070 and confirm timetable, class mode, teacher availability and fees.

References and next steps

Sources and related study guides

Next study Rate of Heat Flow to connect energy quantity with transfer time and pathway. Curriculum scope and sources were checked on 2 August 2026; follow current CDC, NEB and college instructions if requirements change.

Integrated challenge

Separate input energy from useful thermal transfer

A 1.0 kW heater runs for 180 s while 0.50 kg water warms by 60 K. Electrical input is 180 kJ; ideal water gain using c=4200 J kg⁻¹K⁻¹ is 126 kJ. The difference, 54 kJ, is not “lost energy” in the conservation sense: it is transferred to the container and surroundings or remains in other system components. If the chosen useful output is water heating, efficiency is 126/180 = 70%.

Now reverse the question: if the water and kettle together have effective heat capacity 2500 J K⁻¹ and effective useful power 700 W, the initial ideal warming rate is dT/dt=P/C=0.28 K s⁻¹. In reality the rate falls as the temperature difference from the room increases. This connects quantity of heat to the next topic, rate of heat flow, without confusing energy in joules with power in watts.

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